Aneurysms are a fundamental cause of hemorrhagic stroke involving 20% of all stroke cases. In aneurysm ruptures, a portion of the brain is filled blood that can cause tissue death or pressure in the head. Large hemorrhages can be fatal and are cause by clearly visible large aneurysm. A particular case of interest is the debilitating “dementia” like conditions caused by micro hemorrhages that due to small aneurysms ruptures.
Aneurysms are infrequently encountered on a straight, non-branching segment of an intracranial artery. The aneurysms occurring on straight, non-branching segments are more often found to have sacs that point longitudinally along the wall of the artery in the direction of blood flow and to project only minimally above the adventitial surface. Aneurysms having these characteristics are of a dissecting type, rather than of the congenital saccular type, and development of dissecting type aneurysms is heralded more frequently by the onset of ischemic neurological deficits than by the subarachnoid hemorrhage associated with congenital saccular aneurysms.
Detecting small aneurysms is particularly difficult for CTA exams as these are very minute and are often indistinguishable from the vasculature. Additionally, the presence of bone in the skull causes added difficulty to visualize these structures.